Pump cylinder block dampening means



Mam]! 1963 T. BUDZICH 3,082,692

PUMP CYLINDER BLOCK DAMPENING MEANS Filed March 9, 1961 INVENTOR. n4osus 2 5002/01 BY E/CHEfiMCNEA/NYQFAEE/NGTON 2-. A r ro/ewg s UnitedStates Patent 3 082 692 PUMP CYLINDER BLOCiK DAMPENING MEANS TadeuszBudzich, Shaker Heights, Ohio, assignor to The Weatherhead Company,Cleveland, Ohio, a corporation of Ohio Filed Mar. 9, 1961, Ser. No.94,465 7 Claims. (Cl. 103 s7) This invention relates to variable volumepumps and more particularly to a variable volume pump of the typedisclosed in my co-pending application, Serial No. 88,142, filedFebruary 9, 1961.

Variable volume pumps having a plurality of pumping cylinders in acylinder block which is mounted to move so as to vary the effectivepumping stroke provide a number of advantages with respect to efiiciencyin operation, simplicity in construction and low cost to manufacture.Pumps of this type are disclosed in my co-pending application Serial No.825,005, filed July 6, 1959.

It is among the objects of the present invention to provide a pumphaving an elongated housing with an end cap at one end of the housingand a cylindrical wall portion at the interior of the housing adjacentthe end cap and wherein a cylinder block is mounted for axial movementin the housing and the cylinder block is provided with a circularcross-section so as to be guided within the cylindrical portion of thehousing toward and away from the end cap and wherein the space betweenthe cylinder block and the end cap forms a dash-pot chamber fordampening the axial movements of the cylinder block.

In it a further object of my invention to provide a pump according tothe preceding object wherein a passageway is provided through thecylinder block to form a restricted flow path for fluid and wherein theeffective cross-sectional area of such flow path may be varied so as tovary the dampening effect with respect to the cylinder block.

It is a further object of my invention to provide a pump according tothe preceding objects wherein said restricted flow path is in the formof an axial groove along the outer periphery of the cylinder block andwherein a plug carried by the wall of the housing is .adjustablyarranged within said groove and wherein the plug is accessible from theexterior of the housing for varying the flow path.

It is a further object of this invention to provide a pump according tothe preceding objects wherein the plug and groove which provide therestricted flow path also serve as a longitudinal guide for the cylinderblock to prevent rotation of the cylinder block within the pump housing.

Further objects and advantages relating to accuracy in pump control,ruggedness of construction and ease of adjustment will appear from thefollowing description and the appended drawings wherein:

' FIG. 1 is a longitudinal view, partly in section, through a pump madeaccording to my invention;

FIG. 2 is a transverse sectional view taken along the Xine indicated at2-2 of FIG. 1; and

FIG. 3 is a longitudinal sectional view of the cylinder block madeaccording to my invention.

As will be understood by reference to said co-pending applications andas shown in the drawings, a housing 6 is provided with an end capindicated in its entirety as at 7 and a cylinder block indicated at ismounted within the housing 6 for axial movement toward and away from theend cap 7. The interior of the housing 6 is provided with a forwardlydisposed cylindrical wall portion 8 terminating in a shoulder 9 whichserves as an abutment for a shoulder ll on the end cap 7. The in-3,082,692 Patented Mar. 26, 1963 ice is provided with a rearward portion13 which is circular in I cross-section and fits snugly along thecylindrical wall 12. The cylinder block 10 includes a cylindricalportion 14 at the forward end thereof which fits snugly along thecylindrical surface 8 at the interior of the housing. The space on eachside of the cylinder block 10 is filled with fluid at pump inletpressure. Intermediate the wall portions 8 and 12 of the housing are-entrant channel 15 is formed to provide a volume of fluid to bepumped adjacent the outer port 16 for the pumping cylinder 17. It willbe understood that a plurality of pumping cylinders are arranged aboutthe cylinder block identical with cylinder 17. A supporting plate 18 issecured to the housing and serves as a stop or abutment for the end face19 of the cylinder block 10 as the block 10 is retracted from the endcap 7.

A spring 20 is arranged between the end cap 7 and the cylinder block 10so as to normally bias the cylinder block into the retracted position inabutment with the supporting plate 18. Inner ports 21 are provided forthe pumping cylinder 17 and a chamber 22 adjacent the inner ports 21communicates with a bore 23 in supporting plate 18 so as to permit fluidflow from the interior of the housing to the inner port 21 of thepumping cylinder. The inner port 21 and the outer port '16 are formed byinner and outer annular grooves 21a and 16a, respectively. Each pumpingcylinder 17 is provided with a reaction piston 24 which is arranged insealing contact as at 25 with a tubular port member 26. The end cap 7 isprovided with a bore 27 in alignment with each of the pumping cylinders17. This bore is threaded as at 28 to receive a plug 29 serving to holda check valve cage 30 in abutting contact with the tubular port member26.

A check valve plate 31 is biased to closed position by spring 32 carriedwithin the cage 30. The walls of the cage 30 are apertured as at 33 sothat as fluid under pressure from the pumping cylinder 17 unseats thecheck valve plate 31 such fluid is conducted through the apertures 33into the connecting passage 35 and thence into the outlet chamber 36.

A spring plate 37 serves as an abutment for one end of a spring 38surrounding the reaction pistons 24. A

snap-ring 39 and spring abutment ring 40 carried by the reaction piston24 serve as the abutment at the other end of the spring 38. Accordinglyit will be understood that each of the reaction pistons is normallybiased by its spring 38 into sealing engagement with the end face of theport member 26. It will also be understood that fluid pressure in thecylinder is effective across the wall area of the reaction piston 24 tomaintain a pressure seal at 25.

Reciprocating pistons 45 having piston rods 46 are arranged to beadvanced by cam means or the like into the pumping cylinders 17. Springs47 are arranged to retract the pistons 45 from the pumping cylinders 17.The stroke of the reciprocating pistons 45 is fixed accordzingly to theoutput volume of the pump and may be varied by reason of the cut-offposition of the forward end face 45a of the piston 45 with respect tothe ports 16 and 21. Preferably the parts are proportioned with respectto the piston stroke so that when the cylinder. block 10 is at itsmaximum forward position, the piston on the forward limit of its strokedoes' not close oif the application Serial No. 88,142, filed February 9,1961. The control assembly 50 moves toward and away from the end cap 7with the cylinder block 10 by reason of the shoulder 51 and thesnap-ring 52 which holds the control assembly in the central opening 53of the cylinder block 10. A transfer tube 54 is mounted to extend intothe outlet chamber 36 and accordingly fluid at outlet chamber pressureis conducted into the control assembly 50 where such fluid pressure iseffective to determine the position of the cylinder block 10.

It will be understood that the pump housing '6 is filled with fluid tobe pumped out through the outlet chamber 36. The housing is dividedgenerally into a forward chamber as at 60 in front of the cylinder block10 and a rearward chamber as at 70 behind the cylinder block. The fluidon both sides of the cylinder block 10 is at a low or inlet pressure andis adapted to be carried into the inlet ports 16 and 21 of the pumpingcylinders. The only fluid connection or flow passage between the forwardchamber 60 and the rearward chamber 7t} is provided by a rectangulargroove 61 extending axially along the periphery of the forwardcylindrical portion 14 of the cylinder block 110. Since movement of thecylinder block 10 under the action of control means 50 will requirefluid to flow between the chambers 60 and 70 through axial groove 61,the amount of restriction provided by the grooves determines the rate offluid transfer between the chambers 60 and 70 and hence the speed ofresponse of the cylinder block.

The housing 6 is provided with a radial bore 62 threaded at 63 toreceive a plug '64 arranged to project radially into the groove 61 inthe cylinder block 10. Plug 64 has a diameter equal to the width ofgroove 61, so that the only flow passage between the chambers 60 and 70is provided by the space 67 between the end of plug 64 and the bottom ofgroove 61. The plug 64 is provided with a socket head 65 and with anO-ring seal as at 66. Accordingly, it will be understood that by turningthe plug 64 on its threaded connection 63, the plug may be advanced orretracted with respect to the groove 61 to vary the effective area ofthe how passage 67. Thus, the dampening of the axial movement of thecylinder block 10 is conveniently controlled exteriorly of the pumphousing. The plug 64 also functions to guide axial movement of thecylinder block and position it radially within the pump housing 6 sothat each of the pumping cylinders 17 and reaction pistons 24 ismaintained in alignment with its associated port member 26 carried inthe end cap 7.

As described in considerable detail in my co-pending application SerialNo. 88,142, filed February 9, 1961, the control mechanism 50 includes apilot valve member 55 which is moved axially relative to the bore 56 toadmit fluid from the outlet chamber 36 through transfer tube 54 and intoa control chamber 57 and to conduct fluid from the control chamber 57into the interior of the pump housing into space 70. The parts areconstructed and arranged so that when a predetermined high pressure,such as, for example, 2000 pounds per square inch, occurs in the outletchamber 36, fluid at such pressure is directed into the control chamber57 and, by reaction with a surrounding cylinder 58, the cylinder block10 is moved toward its position of minimum output. In the event thefluid pressure in the outlet chamber 36 should drop below suchpredetermined figure of 2000 pounds per square inch, fluid pressure willbe discharged from the control chamber 57 and the cylinder block 10 willbe moved towards its position of maximum displacement by spring 20.

It will be understood by those skilled in the art that the cylinderblock should not be susceptible to hunting or oscillations in responseto fluctuations in fluid pressure at the outlet. The restricted flowpath 67 provided by the groove 61 and the plug 64 guards against huntingand sudden changes in position of the cylinder block 10. For example,even though the control means should respond to a sudden pressureincrease in the outlet chamber 36, the movement of the cylinder block 10will be dampened by the restriction encountered in the fiow passage at67 as the fluid in forward chamber is moved out of chamber 60 intorearward chamber 70. A similar dampening effect occurs on a sudden dropin fluid pres sure at the outlet chamber 36. The spring bias provided bythe spring 20 would normally move the cylinder block 10 quickly towardits position of maximum displacement. Said rapid movement, however, isdampened by fiuid flow from the rearward chamber 70 through therestricted fiow passage 67 into the forward chamber 60.

Although I have shown and described my invention in considerable detail,it will be appreciated by those skilled in the art that numerousvariations may be made therein without departing from the scope of theinvention as defined in the following claims.

What is claimed is:

1. A pump comprising a housing, said housing having an end cap at oneend thereof provided with an outlet chamber, said housing having acylindrical wall portion at the interior thereof adjacent said end cap,a cylinder block mounted for axial movement in said housing, saidcylinder block having a peripheral surface providing cylindricalportions conforming to the cylindrical contour at the interior of thehousing adjacent the outlet, said cylinder block being guided for axialmovement within said housing by sliding movement along said cylindricalsurfaces, said housing having a fluid inlet to fill said housing withfluid to be pumped, said fluid Within the housing being at inletpressure, said cylinder block having a passageway therethroughconnecting that space in the housing between the end cap and thecylinder block to that space in the housing at the other side of thecylinder block whereby movement of the cylinder block is dampened by thefluid flow through said passageway, and adjusting means to vary the areaof said passageway to vary the dampening effect.

2. A pump comprising a housing, said housing having an end cap at oneend thereof provided with an outlet chamber, said housing having acylindrical wall portion at the interior thereof adjacent said end cap,a cylinder block mounted for axial movement in said housing, saidcylinder block having a peripheral surface providing cylindricalportions conforming to the cylindrical con tour at the interior of thehousing adjacent the outlet, said cylinder block being guided for axialmovement within said housing by sliding movement along said cylindricalsurfaces, said housing having a fluid inlet to fill said housing withfluid to be pumped, said fluid within the housing being at inletpressure, said cylinder block having an axial groove along its peripheryto provide a path therethrough connecting that space in the housingbetween the end cap and the cylinder block to that space in the housingat the other side of the cylinder block whereby movement of the cylinderblock is dampened by the fluid flow through said passageway, saidhousing having an adjustable member in the wall thereof extending intosaid groove to adjust the size of the fluid flow path thereaiong.

3. A pump comprising a pump housing, a cylinder block slidably mountedwithin said housing for axial movement therein, said cylinder blockproviding a seal dividing the interior of said housing into first andsecond chambers, an outlet on said pump housing, an inlet to theinterior of said pump housing opening into one of said chambers, aplurality of axially aligned cylinder bores in said cylinder block, apiston in each of said cylinder bores, means to reciprocate said pistonsin said cylinder bores, port means to admit fluid into said cylinderbores, means connecting each of said cylinder bores to said outlet, arestricted passage in said cylinder block r interconnecting said firstand second chambers, and adjusting means to vary the area of saidrestricted passage.

4. A pump comprising a pump housing, a cylinder block slidably mountedwithin said pump housing for axial movement therein, said cylinder blockbeing formed to provide a seal dividing the interior of said housinginto first and second chambers, an outlet on said pump housing, an inletto the interior of said pump housing opening into one of said chambers,a plurality of axially aligned cylinder bores in said cylinder block, apiston within each of said cylinder bores, means to reciprocate saidpistons in said cylinder bores, port means to admit fluid into saidcylinder bores, means connecting each of said cylinder bores to saidoutlet, an axial groove extending along the outer periphery of saidcylinder block adja cent said pump housing and interconnecting saidfirst and second chambers, and adjusting means to vary thecrosssectional area of said axial groove.

5. A pump comprising a pump housing, a cylinder block slidably mountedwithin said housing for axial movement therein, said cylinder blockbeing formed to provide a seal dividing the interior of said housinginto first and second chambers, an outlet on said pump housing, an inletto the interior of said pump housing opening into one of said chambers,a plurality of axially aligned cylinder bores in said cylinder block, apiston in each of said cylinder cores, means to reciprocate said pistonsin said cylinder bores, port means to admit fluid into said cylinderbores, means connecting each of said cylinder bores to said outlet, anaxial groove on the outer periphery of said cylinder blockinterconnecting said first and sedond chambers, and a guide pin mountedon said pump housing to project into said axial groove and adapted toprevent relative rotation between said cylinder block and said pumphousing, said guide pin reducing the efiective passage area of saidaxial groove to restrict fluid flow between said first and secondchambers.

6. A pump comprising a pump housing, a cylinder block slidably mountedwithin said housing for axial movement therein, said cylinder blockproviding a seal dividing the interior of said housing into first andsecond chambers, an outlet on said pump housing, an inlet to theinterior of said pump housing opening into one of said chambers, aplurality of axially aligned cylinder bores in said cylinder block, apiston in each of said cylinder bores, eccentric cam means toreciprocate said pistons in said cylinder bores, port means to admitfluid into said cylinder bores, means connecting each of said cylinderbores to said outlet, an axial groove on the outer periphery of saidcylinder block interconnecting said first and second chambers, a guidepin adjustably secured to said pump housing to project into said axialgroove and revent relative rotation between said cylinder block and saidpump housing and to reduce the effective passage area of said axialgroove, whereby adjustment of said guide pin within said pump housingvaries the efiective area of said axial groove.

7. A pump comprising a pump housing, a cylinder block slidably mountedwithin said pump housing for axial movement therein, said cylinder blockproviding a seal dividing the interior of said housing into first andsecond chambers, an outlet at one end of said pump housing, an inlet tothe interior of said pump housing opening into one of said chambers, aplurality of axially aligned cylinder bores in said cylinder block, apiston within each of said cylinder bores, eccentric cam means toreciprocate said pistons in said cylinder bores, port means in saidcylinder block to admit fluid into said cylinder bores, means connectingeach of said cylinder bores to said outlet, an axial groove on the outerperiphery of said cylinder block adjacent said pump housing tointerconnect said first and second chambers, a plug threadedly engagedin said pump housing and extending radially into said axial groove toreduce the effective passage area of said groove, whereby the depth ofengagement of said plug in said axial groove is adjustable by threadedrotation of said plug in said pump housing.

References Cited in the file of this patent UNITED STATES PATENTS2,990,781 Tuck et a1. July 4, 1961 FOREIGN PATENTS 1,202,109 France June20, 1959

1. A PUMP COMPRISING A HOUSING, SAID HOUSING HAVING AN END CAP AT ONEEND THEREOF PROVIDED WITH AN OUTLET CHAMBER, SAID HOUSING HAVING ACYLINDRICAL WALL PORTION AT THE INTERIOR THEREOF ADJACENT SAID END CAP,A CYLINDER BLOCK MOUNTED FOR AXIAL MOVEMENT IN SAID HOUSING, SAIDCYLINDER BLOCK HAVING A PERIPHERAL SURFACE PROVIDING CYLINDRICALPORTIONS CONFORMING TO THE CYLINDRICAL CONTOUR AT THE INTERIOR OF THEHOUSING ADJACENT THE OUTLET, SAID CYLINDER BLOCK BEING GUIDED FOR AXIALMOVEMENT WITHIN SAID HOUSING BY SLIDING MOVEMENT ALONG SAID CYLINDRICALSURFACES, SAID HOUSING HAVING A FLUID INLET TO FILL SAID HOUSING WITHFLUID TO BE PUMPED, SAID FLUID WITHIN THE HOUSING BEING AT INLETPRESSURE, SAID CYLINDER BLOCK HAVING A PASSAGEWAY THERETHROUGHCONNECTING THAT SPACE IN THE HOUSING BETWEEN THE END CAP AND THECYLINDER BLOCK TO THAT SPACE IN THE HOUSING AT THE OTHER SIDE OF THECYLINDER BLOCK WHEREBY MOVEMENT OF THE CYLINDER BLOCK IS DAMPENED BY THEFLUID FLOW THROUGH SAID PASSAGEWAY, AND ADJUSTING MEANS TO VARY THE AREAOF SAID PASSAGEWAY TO VARY THE DAMPENING EFFECT.